Field
This disclosure relates to well testing and more particularly to methods and apparatuses for performing and interpreting production test measurements.
Description of the Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore is drilled, the well may be tested for purposes of determining the reservoir productivity and other properties of the subterranean formation to assist in decision making for field development. Various components and equipment may be installed in order to monitor and conduct flow tests while producing the various fluids from the reservoir.
Well testing is done to provide reservoir characterization, estimation of well deliverability, evaluation of well completion and perforation strategy, and assess efficiency of performed operations on a well, such as drilling, completion, perforation, stimulation, etc. During a well test, one parameter obtained is the flow rate measured at the surface. Various types of analysis may be performed on the results of the flow tests to determine formation, fluid, and flow characteristics, such as on the data measured using flowmeters. Wells often produce a combination of water, oil and gas, making flow rate measurements rather complex.
One conventional way of measuring the flow rate is by separating fluid phases in a multiphase flow and then measuring the individual phases with single phase flowmeters. Separation into and measuring of single phase flows are generally considered very accurate. Although single phase flow measurements are generally trustworthy, a difficulty arises when separation of the fluids is incomplete, thus providing a mixture of fluid phases (e.g., gas bubbles in oil) to be measured by a single phase flowmeter and inaccurate results. Another potential drawback is that a lot of information about the behavior of the fluid flow in the production well may be missed, as fluid flow rate is measured after separation. Consequently, the desire arose to measure the multiphase flow rate before separation using a multiphase flowmeter. However, multiphase flow measurement is very complex and its development for industrial use has been relatively recent.